HP 3000 Manuals HP 3000 Manuals
Opening a File Mapped
Example 11-1 illustrates how a file is created and opened with
short-mapped access. This HP Pascal/XL program segment opens the file,
then writes data to the file with assignments to the array structure.
The procedure then sets the EOF and closes the file.
The file is then reopened short-mapped, and data is retrieved before the
file is closed and purged.
Example 11-1. Opening a Mapped File
procedure Mapped_File_Example;
type
record_t = record {** defines an 80-byte record **}
a_record : packed array [1..80] of char;
end;
file_t = array [1..50000] of record_t;
{** define a 4,000,000 byte array **}
var
access,domain : integer;
dummy : shortint;
file_name : packed array [1..20] of char;
file_number : integer;
file_ptr :^file_t; {** pointer to the file **}
filesize : integer;
index, rec : integer;
create_domain_perm : integer;
read_write_access : integer;
domain_old : integer;
status : record
case integer of
0: (all: integer);
1: (info: shortint;
subsys: shortint);
end;
const
file_name_option = 2;
domain_option = 3;
filesize option = 35;
short_mapped_option = 18;
access_type_option = 11;
begin
{** initialize item values for the HPFOPEN **}
file_name := '%EXAMPLE%';
create_domain_PERM := 4;
domain_OLD := 3;
filesize := 15265;
read_write_access := 4;
{** create a short-mapped file **}
HPFOPEN (
file_number, status,
file_name_option, file_name
domain_option,create_domain_PERM,
filesize option, filesize,
short_mapped_option, file_ptr,
access_type_option, read_write_access,
);
{** put some data into the file **}
for rec := 1 to 100 do
for index := 1 to 80 do
file_ptr^[rec].a_record[index] :=
Chr (((rec - 1) Mod 26) + 65);
{** set the logical record pointer **}
FPOINT (file_number, 33);
FCONTROL (file_number, 6, dummy); {** set the EOF **}
FCLOSE (file_number, 0, 0); {**close the file **}
{** re-open the same short-mapped file **}
HPFOPEN (
file_number, status,
file_name_option, file_name,
domain_option, domain_OLD,
short_mapped_option, file_ptr,
);
{** retrieve some data you put in file **}
for rec := 1 to 100 do
begin
write ('Record-', rec:4, ' ');
for index := 1 to 20 do
write (file_ptr^[rec].a_record[index];
writeln;
end;
{** close and purge the file **}
FCLOSE (file_number, 4, 0);
end;